Gizmodo : Blacklist Numbers to Prevent Drunken Dialing:
"Virgin Mobile is aiming to prevent drunken dialing in Australia by providing a way to blacklist numbers so that they can't be called until 6AM. According to a survey by the company, over 95 percent of drinkers make phone calls after imbibing, with 30 percent of calls going to the most dreaded of recipients: ex-partners."